大比丘三千威儀 1.36

1.36

當念有五事：一者當念佛功德、二者當念佛經戒、三者當念佛智慧、四者當念佛恩大難報、五者當念佛精進乃至泥洹。

One should mindfully contemplate five matters: first, one should contemplate the merits of the Buddha; second, one should contemplate the sutras and precepts of the Buddha; third, one should contemplate the wisdom of the Buddha; fourth, one should contemplate the benevolence of the Buddha as being immense and difficult to repay; fifth, one should contemplate the vigor of the Buddha culminating in nirvāṇa.